Enhancement: SDL2 support

[BenjamenMeyer]

Vega Strike is moving to use SDL2. Add support to the docker images for SDL2 in addition to SDL1.

• add a tool to easily check that the script works locally
• ignore Vi Swap files

Thank you for submitting a pull request and becoming a contributor to Vega Strike's Build System Docker Images.

Please answer the following:

Code Changes:

• This is a documentation change only
• CI Change

Issues:

• VS Engine SDL2 Support

Purpose:

• What is this pull request trying to do? Adds SDL2 Dev libraries
• What release is this for? Adding SDL2 support
• Is there a project or milestone we should apply this to? 0.9.x

[BenjamenMeyer]

NOTE: We already removed Kinetic from the VS Engine repo.

[royfalk]

Looks fine to me. I did remember that I needed to touch this repo as well but wasn't sure when to do it (before or after) we merge the main PR.
One comment - should we keep sdl1.2?

[royfalk]

Other than my comment about SDL1.2, it looks fine.

[BenjamenMeyer]

Keeping the SDL 1.x for now. We still have releases that use it . We can clean that up after 0.9.x gets released